ASTM_D_6342_-_22.pdf

Designation:D634222Standard Practice forPolyurethane Raw Materials:Determining Hydroxyl Numberof Polyols by Near Infrared(NIR)Spectroscopy1This standard is issued under the fixed designation D6342;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This standard covers a practice for the determination ofhydroxyl numbers of polyols using NIR spectroscopy.1.2 Definitions,terms,and calibration techniques are de-scribed.Procedures for selecting samples,and collecting andtreating data for developing NIR calibrations are outlined.Criteria for building,evaluating,and validating the NIRcalibration model are also described.Finally,the procedure forsample handling,data gathering and evaluation are described.1.3 The implementation of this standard requires that theNIR spectrometer has been installed in compliance with themanufacturers specifications.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.NOTE1This standard is equivalent ISO 15063.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD4274 Test Methods for Testing Polyurethane Raw Materi-als:Determination of Hydroxyl Numbers of PolyolsE131 Terminology Relating to Molecular SpectroscopyE168 Practices for General Techniques of Infrared Quanti-tative AnalysisE222 Test Methods for Hydroxyl Groups Using AceticAnhydride AcetylationE1655 Practices for Infrared Multivariate QuantitativeAnalysisE1899 Test Method for Hydroxyl Groups Using Reactionwith p-Toluenesulfonyl Isocyanate(TSI)and Potentiomet-ric Titration with Tetrabutylammonium Hydroxide2.2 ISO Standard:ISO 15063 PlasticsPolyols for use in the production ofpolyurethanesDetermination of hydroxyl number byNIR spectroscopy3.Terminology3.1 DefinitionsTerminology used in this practice followsthat defined in Terminology D883.For terminology related tomolecular spectroscopy methods,refer to Terminology E131.For terms relating to multivariate analysis,refer to PracticeE1655.3.2 Definitions of Terms Specific to This Standard:3.2.1 hydroxyl numberthe milligrams of potassium hy-droxide equivalent to the hydroxyl content of 1 g of sample.4.Summary of Practice4.1 Multivariate mathematics is applied to correlate the NIRabsorbance values for a set of calibration samples to therespective reference hydroxyl number for each sample.Theresultant multivariate calibration model is then applied to theanalysis of unknown samples to provide an estimate of theirhydroxyl numbers.4.2 Multilinear regression(MLR),principal componentsregression(PCR),and partial least squares regression(PLS)are the mathematical techniques used for the development ofthe calibration model.4.3 Statistical tests are used to detect outliers during thedevelopment of the calibration model.Outliers can includehigh leverage samples and samples whose hydroxyl numbersare inconsistent with the model.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.22 on Cellular Materials-Plasticsand Elastomers.Current edition approved July 1,2022.Published July 2022.Originally approvedin 1998.Last previous edition approved in 2017 as D6342-12(2017)1.DOI:10.1520/D6342-22.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.14.4 Validation of the calibration model is performed byusing the model to analyze a set of validation samples.Thehydroxyl number estimates for the validation set are statisti-cally compa